Lipid Emulsification and Degree of Unsaturation

Experiment 4.1: Lipid Emulsification and Degree of unsaturation        02/14/2017

Salida Ali 5880653

Siradanai Kanithasevi 5780171

Yin May Tun 5780487

Abstract

        The experiment is divided into two parts. The purpose of the first part of the experiment is to observe the effect of adding an emulsifier into a water and oil solution. Three test tubes with 1 ml of oil and 1 ml of water are prepared. 5 drops of tween-80 and 5 drops of liquid soap and added into the second and third tube respectively. The results show a layer formation and the tube with an emulsifier has a larger opaque white layer than translucent clear layer after 30 minutes. The test tube with tween-80 has a largest opaque white layer among the three tubes; thus, we conclude that tween-80 is the better emulsifier. The purpose of the second part of the experiment is to determine the degree of unsaturation among all the samples. 6 test tubes with different samples are prepared. Then we add 1 drop of iodine/KI solution to the tube and heat them. The time elapsed for the color of the iodine to change back to its original is recorded. Our results showed that coconut oil has the most unsaturation while lard has the least unsaturation. Since the experiment is prone to error, we compared our result with the structure of each sample. The structure shows that soybean has the most unsaturation while lard has the least unsaturation. We conclude that we need a more well-define experiment to determine the degree of unsaturation since our result and the results from the structure do not have a high reliability.

Introduction

Emulsifiers are molecules with both polar and nonpolar domains (Dangkulwanich, 2017, exp 4.1). They are capable of interacting with both water and lipid causing them to be mixed and dispersed in each other; this creates a stable, homogenous smoothing emulsion (Food-info, 2014). Detergents, for example, have one hydrophobic head and one hydrophilic tail. Unlike phospholipid, which has two hydrophilic tails, detergents form micelle instead of a bilayer due to its cone-like geometry (Tymoczko et al, 2015).  In this experiment, we are going to use detergent tween-80 and liquid soap as our emulsifier. Tween-80, or polysorbate 80, is manufactured by reacting with oleic acid and polyethoxylated sorbitan (NCBI – CID=443315, n.d). Soaps are comprised of sodium or potassium salts with long-chain fatty acids. Soaps cleanse by lowering the surface tension of water, resulting in emulsification of oil and grease (Sakharkar, 2013).

 In the first experiment, we want to observe the emulsification of cooking oil and water by tween-80 and liquid soap.  The tubes are separated into the one with and without an emulsifier. At the first few seconds, we expect to see layer formation in all the test tubes. After a few minutes, we expect the same layer in the tube without an emulsifier and see less of a layer in the tubes with an emulsifier. We also want to compare which of the two emulsifiers is the better one. We hypothesized that tween-80 would be the better since tween-80 is often used in food, cosmetic, and pharmaceutical industries (NCBI – CID=443315, n.d.). Since tween-80 is a better emulsifier, we expect to see a faster rate of the disappearance of the layer.

In the second experiment, we will use a spectroscopic method to analyze the degree of unsaturation. Fatty acids are classified as saturated or unsaturated, classified by the presence of double bonds. Lipid saturation can be tested with halogens such as bromine or iodine (Tymoczko & et al, 2015). Halogenation is the process where elimination of double bonds occurs along with the addition of two atoms of the halogen either on the same plane or opposite plane if the halogen attacks a trans double bond or cis double bond, respectively (Vollhardt & Schore, 2014). We use iodine with the aid of heat for halogenation in this experiment. If the lipid is unsaturated, halogenation will occur and the color of the solution will change (Dangkulwanich, 2017, exp 4.1). The faster the disappearance of the color, the more unsaturated the lipid is. We hypothesized that soybean oil would have the highest degree of unsaturation because it is liquid at room temperature. On the other hand, lard would have the lowest degree of unsaturation because it is solid at room temperature.

Material and Method

        In the first part of the experiment (Dangkulwanich, 2017), we used tween-80, with a molecular weight of 604.8 g/mol (NCBI – CID=443315, n.d), as a surfactant. Then we prepared 3 test tubes with the solution summarized in the following table.

After preparing the solutions, we used our thumb to cap each test tube then shake them rigorously. After that, we placed the tubes in a rack, and then make an observation after 1 minute, 5 minutes, and 30 minutes. We could analyze the results by observing the layer formations in each tube after each time interval.

In the second part of the experiment (Dangkulwanich, 2017), we prepared 6 test tubes containing soybean oil, veg. shortening, coconut oil, olive oil, lard, and oleic acid, which has a molecular weight of 282.468 g/mol (NCBI – CID=445639, n.d.). We need to observe the original color of the lipid (The color will change after the iodine/KI solution is added). Then we added 1 drop of iodine/KI solution to the tubes and mix the tubes by flicking them. The color in the tubes will change. We placed the tubes in a hot water beaker simultaneously and started the timer immediately. When the color of the iodine disappeared and the color of the solution turns back to its original color, we stopped the timer and record the time relapse.